The invention relates to those devices used for winding up and/or unwinding coils of material during some industrial processes, as occurs, for example, during rolling of certain metal strips.
A typical example of the application of these devices is for multi-cylinder or Sendzimir cold-rolling mills.
In such rolling mills the strips are conveyed back and forth between a pair of opposite rotating rolls which are mounted inside a supporting stand, together with a series of reinforcing rolls according to the well-known xe2x80x9cclusterxe2x80x9d arrangement used in Sendzimir technology.
During each pass the strip to be rolled is unwound from a coil and wound onto another one, at opposite sides of the supporting stand: for this purpose the aforementioned coils are mounted on respective winding devices, commonly called xe2x80x9cswiftxe2x80x9d, to which the present invention relates.
These devices comprise a rotating spindle onto which the strip of the coils is wound (or unwound) and which is actuated by an associated motor, usually of the electric type, and, if necessary, a speed-reduction system depending on the circumstances.
The spindle can expand radially so as to lock the coil wound on it, exerting a force internally against its wound turns; this allows high torques to be applied to the coil so as to exert on the strip a tensile force which in Sendzimir rolling mills may reach values of a few tens of tonnes.
When rolling has been completed, the spindle is brought back into a retracted condition so as to allow extraction of the coil, which is performed by removing the latter axially from the spindle.
An important feature of the Sendzimir rolling process is the need for having coils where the strip is wound in a regular manner.
Indeed, if the coils to be rolled have winding defects, for example typically when the edges of the wound turns of strip material are not properly aligned so as to produce an arrangement which may be described as xe2x80x9ctelescopicxe2x80x9d, the risk of the strip breaking during rolling with a consequent interruption in the production cycle, increases substantially.
In this connection it should be pointed out that the Sendzimir rolling process is performed under fairly critical conditions for the strip, which is not only subject to the high tensile force mentioned above, but also to a feed speed between the working rolls in the order of 1000 m/min.: these parameters therefore require very precise working conditions in order to avoid breakage of the strip and therefore any defects, such as that mentioned above concerning winding of the coils, are not acceptable.
At present to overcome this drawback, in Sendzimir rolling mills the non-uniform coils before being processed are arranged on a special unwinding reel (see FIG. 1).
The latter is located sideways one of the two winding devices 2 and has its axis parallel to that of its spindle; it is also mounted on a carriage 3, whose wheels 4 move along rails 5 arranged parallel to this axis.
In this manner an irregular coil is unwound, at the beginning of the rolling operation, from the reel 1, causing the strip 6 to perform a first pass between the working rolls 7 at a low feed speed and under reduced tension; the strip is then wound up onto the farther winding device 2.
As the strip 6 is unwound from the reel 1, the carriage 3 on which it is mounted is displaced along the rails 5 so as to compensate for any irregularities in the coil wound on the reel; in other words, the movements of the carriage allow the strip to be unwound while keeping its edges aligned in a straight reference direction.
Consequently, the strip may be wound up again onto the spindle of the farther device 2, without the danger of producing turns having edges not aligned with each other.
Such a solution makes it possible to obtain the proposed result of uniformity of the coils wound onto the spindles of the winding devices; however, it has some important drawbacks.
First of all it can be easily seen that the rolling mill must be provided with a whole series of special equipment, including the carriage movable along rails and the reel mounted thereon, these being used only during the first pass of the strip carried out in order to eliminate the winding defects in the initial coil.
As a consequence it can be easily understood that this fact increases substantially the complexity of the whole plant, making it also disadvantageous from the point of view of exploiting its components, since some of them (i.e. the reel mounted on the carriage and the other apparatuses such as those shown in FIG. 1) operate only during the initial stage of the production cycle and are no longer used for rolling the strip material.
It is also obvious that the space required for installing the special equipment referred to above, increases significantly the overall dimensions of the entire rolling mill.
Finally, it must also be taken into account that the duration of the production cycle is increased by the step of unrolling the strip from the reel, which occurs at a slow strip feeding speed and under a tension less than that used during the actual rolling step, i.e. when the strip is wound onto one device 2 and unwound from the other device passing in between the working rolls 7.
An improvement to such state of the art can be found in U.S. Pat. No. 3,477,655 which discloses a winding device wherein the spindle is driven by a speed reducer gearing system.
It is therefore the object of the present invention to remedy this situation.
In other words, its object is to provide a winding device having structural and operating features such that it is also able to work with coils wound non-uniformly, without the need for the abovementioned special equipment, in particular the reel mounted on the carriage movable along rails.
This object is achieved by a winding device whose features are set out in the appended claims.